In the field of the production of knitted tubular articles with circular knitting machines for hosiery or the like, in some cases it is necessary to transfer the article from the machine used to produce it to another production unit in order to perform on the article additional work that cannot be performed on said machine or that it is not economically convenient to perform on said machine.
In particular, in the field of the production of hosiery, in recent years techniques have been developed for automated toe closing by sewing or looping. Some of these techniques are based on picking up the article from the machine used to produce it and on transferring it to a station for further work, which is distinct with respect to the production machine, so as to close the toe of the hosiery item in the station for further work, while the machine is used to produce another hosiery item. These techniques have the advantage, with respect to other techniques based on closing the toe of the hosiery item directly on the machine used to produce it, of not penalizing excessively the productivity of the machine.
The transfer of the hosiery item, or more generally of the tubular article, from the machine used for its production to the station in which the closure of an axial end of the article, or more generally additional work, must be carried out, is generally performed by means of a pick-up device, which by means of pick-up members individually grips the loops of knitting of the article from the needles of the machine and retains them during the transfer of the article.
In some toe closing techniques, the pick-up device is also used to support the article during the execution of the additional work, while in other techniques the pick-up device is used exclusively to transfer the article, since once it has reached the station where the additional work is to be done it releases, usually again in an individual manner, the loops of knitting picked up previously from the needles to another device that is designed to support the article during execution of the additional work, such as for example a handling device. Such handling device arranges the loops that belong to one half of the row of knitting received from the pick-up device so that they face the loops that belong to the other half of said row of knitting and supports the two half-rows of knitting in a mutually facing position during the intervention of a sewing or looping head that joins the pairs of mutually facing loops of knitting.
In known types of pick-up devices used to simply transfer the article from the machine that produces it to a handling device, the coupling between the pick-up members and the needles, in order to transfer the loops of knitting from the needles to the pick-up members, usually occurs by inserting the head of the needle in a seat formed in the end of the pick-up member. For that reason, the pick-up device usually has an annular pick-up body, designed to face coaxially the end of the needle cylinder from which the heads of the needles protrude and which supports a plurality of pick-up members oriented parallel to the axis of the pick-up body.
A pick-up device of this type is disclosed for example in EP0942086.
In devices of this type, the coupling between one end of the pick-up members and the head of the corresponding needle requires high precision both in the provision of the pick-up device as a whole and in the positioning of the pick-up body with respect to the needle cylinder of the machine and of the pick-up members with respect to the needles.
Moreover, the arrangement of the pick-up members, as well as the presence of any members for actuating them, entails a relatively large space occupation of the pick-up body along a direction that is parallel to the axis thereof. This relatively large space occupation can cause problems in positioning the pick-up body with respect to the machine in order to pick up the article. In order to be able to arrange the pick-up body so that it faces the needle cylinder of the machine, in the case of single-cylinder circular machines, it is in fact necessary to lift the dial and the yarn guides that are used to provide the needles with the yarns required to manufacture the article. This lifting can cause tangling of the yarns and accordingly cause problems when knitting on the machine resumes.
If the pick-up device is used with double-cylinder circular machines, the problems generated by the axial space occupation of the pick-up body are even greater, since in this case the pick-up body must be arranged between the two needle cylinders by first lifting the entire upper needle cylinder and the members connected thereto.